Paperboard container closure



NOV 26, 1968 M. w. MILLER ETAL 3,412,922

PAPERBOARD CONTAINER CLOSURE] Filed Sept. 6, 196

A TTORNE Y United States Patent O 3,412,922 PAPERBOARD CONTAINER CLOSURE Melvin W. Miller, Detroit, and Duncan J. Crawford,

Franklin, Mich., assignors to EX Cell- Corporation Continuation-impart of application Ser. No. 456,651,

Apr. 26, 1965. This application Sept. 6, 1966, Ser.

3 Claims. (Cl. 229-37) ABSTRACT OF THE DISCLOSURE An improved container bottom closure having a foldunder tab in the middle of the tuck-in flap so designed that by using the closure structure and length of the tab forming slits the bottom closure is sealed from edge wicking.

This application is a continuation-in-part of application Ser. No. 450,651, filed Apr. 26, 1965, now U.S. Patent No. 3,294,310.

This invention relates to thermoplastic coated paperboard containers, and more particularly to an improved thermoplastic coated paperboard container bottom closure for eliminating edge wicking through the exposed panel edges in the interior container.

In our prior application we disclosed a container 1n which the interior cut edges were folded under to form sealed edges thereby rendering them impervious to moisture so that the edge wicking action of the liquid product is eliminated. While the container proved satisfactory in solving the edge wicking problem it necessitated increasing the size of certain of the panels to provide sufficient material to be folded under and yet retain enough overlap area to insure a proper heat seal. It can be appreciated that any increase in the size of the container blank, however, small, when measured against the total container output for a year results in a considerable increase in the cost of material.

An equally important consideration is that any increase in the total number of superimposed layers of sheet material in the container results in increased difficulty during the forming and pressure heat sealing operation performed by the container.

Accordingly, it is an important object of the present invention to provide an improved coated paperboard container in which the raw edges inside of the container have been eliminated so as to provide a container having a long shelf life.

It is another object of the present invention to provide a coated paperboard container blank in which the overall width of the container blank has not been increased.

It is -a further object of the present invention to provide a coated paperboard container in which the interior cut edges of the bottom closure have been folded under to form sealed edges which are impervious to moisture, and wherein edge wicking action is eliminated while having a minimum of superimposed layers of material.

It is still another object of the present invention to provide a novel and improved coated paperboard container bottom closure in which incipient liquid channels are sealed while employing the same construction to eliminate the raw edges of the container bottom closure so as to provide a container having a long shelf life.

Other objects, features and advantages of this invention will be apparent from the following detailed description, appended claims, and accompanying drawings.

In the drawings:

FIG. 1 is a lay-out View of a thermoplastic coated paperboard blank from which a container bottom closure ACC of the present invention is formed, and showing the inside surface thereof;

FIGS. 2 and 3 are fragmentary perspective views illustrating sequentially two of the Steps in forming the bottom closure formed from the blank of FIG. l.

FIG. 4 is a view of the inside face of the Completed container bottom closure.

FIG. 5 is an enlarged sectional view along the line 5-5 of FIG. 4.

Referring now to the drawings, the numeral 10 generally indicates -a coated paperboard container made in accordance with the principles of the present invention. The container described in this application is made from paperboard having a polyethylene coating thereon but it should be understood that other suitable heat sealable thermoplastic coatings may be employed as a coating for the container.

Referring more specifically to FIG. 1, the container 10 is shown in flat blank form with a pattern of 'appropriate score lines and having the inside surface of the blank showing. The container blank is separated into three vertically disposed groups of panels by the score lines 11 and 12. The material above the score line 11 is termed the top closure, the material between the score lines 11 and 12 is termed the body panel group and the material below the score line 12 is termed the bottom closure panel group. The body panel group comprises the four panels indicated by the numerals 13, 14, 15 and 16, and the side seam flap 17. The container blank is defined on the sides by the edges 18 and 19. The body panels 13-16 are separated by the score lines 26-29.

FIG. l shows the side seam flap 17 provided with a fold or score line 9 about which is folded the outer portion 17a of the flap 17, and shows the flap portion 17a being folded under the remaining portion 17b of the side seam ap 17 to a completely folded over portion. As shown in FIG. l, the raw edge of the side seam 19 is folded under to the position 19a `so that it is not exposed when the container blank is folded to form a flat side seam container blank as shown in FIG. 4.

The top closure contains the end panels 20, 21 and the roof panels 22, 23. The end panel 20 is connected to the fold-back panels 30, 31 at the score lines 41, 42 respectively. The end panel 21 is connected to the fold-back panels 32, 33 at the `score lines 43, 44, respectively. Secured to the fold-back panels 30, 31, at the score line 34, are the inner rib panels 35, 36, respectively. The inner rib panels 35, 36 are connected lat the score line 39. The fold-back panels 32, 33 are connected to the inner rib panels 37, 38, respectively, at the score line 34. The inner rib panels 37, 38 are connected at the score line 40.

The roof panels 22, 23 are attached to the outer rib panels 45, 46, respectively, at the score line 34. The outer rib panels 45, 46 are provided with the sealing flaps 47, 48, respectively, The roof panels 22, 23, include the pouring spout flap portion 51, 52 which are formed by the score lines 49, 50, respectively.

The bot-tom closure panel group comprises the panels 55-58. The bottom clossure panels 55, 57 are substantially square plan configuration. The bottom closure panels 56, 58 are substantially triangular in plan conguration. The bottom closure panel 55 is provided with an extended tuck-in ap 59, and the bottom closure panel S7 is provided with an extended tuck-out or tuck-over ap 60. The bottom closure panel 56 is connected to the adjacently disposed substantially triangular fold-back panels 61, 62 at the score lines 65, 66, respectively. The bottom closure panel 58 is connected to the adjacently disposed substanlsially triangular fold-back panels 63, 64 at the score lines The forming, filling and sealing of the container 10 is 3 shown in detail in U.S. Patent Nos. 3,002,328; 3,120,335 and 3,166,994. These patents are assigned to the assignee of the subject application and the disclosures thereof are incorporated by reference for a more complete description of the container.

As was explained in our previous application the container raw edges of the panels exposed to the product inside the container can be folded under so as to prevent wicking. In the case of raw edge of tuck-in flap 59 it was disclosed that the entire edge be folded under, thereby necessitating an initially wider flap 59 if the same heat seal area employed in the existing liquid tight container closure, shown in U.S. Patent 3,120,335, is to be maintained. In actual practice, however, it was discovered that a weakened heat seal resulted due to the discontinuity at the transition area between the outside and inside bonding surfaces of the tuck-under flap 59 that is heat sealed to the tuck-over fiap 60. Not only is there an inherent channel area that cannot be sealed, but the build-up of paperboard thicknesses along portions of the seal render the sealing pressure pad less effective in operation.

The present application shows a fold-under tab 70 located on the tuck-in flap 59 and formed by a pair of slits 71, 72 which are preferably made during the cutting and scoring phase of the blank production. The blank is also scored at 73 so that the tab 70 can be easily folded back against the outside surface of said panel 55 during the formation of the container bottom closure (FIGURE 2).

As can be seen in FIGURE 4 the flap portions 59a and 59b are located in the same relative positions as the standard tuck-under flap of the container closure shown in the U.S. Patent 3,120,335, issued to H. B. Egleston and C. Z. Monroe, and, therefore, provide adequate heat sealing areas to achieve a strong closure construction. Also, by folding-under the central tab 70 to form sealed edge 77, applicants have attained a sealed closure that is protected against wicking by the liquid product.

Referring to FIGURE 1, it will be noted that the overall width dimension D of tuck-in fiap 59 exceeds the length of slits 71, 72, denoted by the dimension F The reference .character W denotes the length of tab 70 and is approximately two-fifths the overall width of the closure panel 55 denoted by character L.

In the case of the quart, pint, and one-half pint series of containers, a typical dimension for D would be about .310 inch while F would be about .210 inch. By virtue of this relationship it can be seen in FIGURE 4 that the sealed edge 77, formed by folding under tab 70, is located afdefined distance past the axis of symmetry A of the closure.

The reason for this construction is explained by the fact that while cut or raw edges 85, 86 abutt and are crowded together along the axis A to seal their edges there still remains the possibility of incipient fluid escape channel forming at the juncture 83, 84 of the edges. By locating the sealed edge 77 as shown the remaining portion of the inner surface of ap 59 adjacent edge 77 forms a sealing face which bonds with adjacent portion of panel 61, 62, 63 and 64 to insure closure of junctures 83, 84 against the liquid product.

The cross-sectional view of FIGURE 5 shows the relationship of the sealed layers positioned in accordance with the invention. Cut edge 76 is shown spaced inwardly from edge 78 so that sealed edge 77 falls past the junction 83 a distance sufficient to bridge and seal the juncture. It should also be noted that the Width W of the tab 70 indicated in FIGURE l is approximately two-fifths the length L of end panel 5S and thereby spaced equally from the panel 55 boundaries 18 and 26.

The raw edge 19 of side seam panel 17 can be sealed in various ways and is shown in the present embodiment as being folded under merely for the purposes of illustration. It will be seen that a coated paperboard container provided with folded edges in accordance with the present 1. In a container of paperboard or the like having an overall surface of thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising the combination of a tubular body having a side seam ap, a top closure on said body, first and second parts of opposed bottom closure panels connected to said body, said second pair of bottom closure panels being triangular ,in shape and infolded between said body and said first pair of bottom closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said first pair of opposed bottom closure panels, said fold-back panels being folded against the inside surface of said first pair of opposed bottom closure panels Vand with adjacent edges of each pair of fold-back panels abutting each other, a tuck-in fiap integral with one of said first pair of bottom closure panels and inserted between the other bottom closure panel of said first pair and the fold-back panels thereagainst, a tuck-over flap integral with and extending over the other one of said first pair of bottom closure panels, said tuck-over flap extending over and beyond said tuck-in fiap, the improvement therein comprising:

(a) said tuck-in flap having a pair of spaced parallel slits extending normal to the free edge thereof so as to define a fold-under tab in the middle of said tuckin fiap,

(b) said pair of slits extending a distance that is approximately two-thirds of the width of said tuck-in flap, wherein when said fold-under tab is folded against the outer surface of its associated bottom closure panel the free edges of said tab are sealed in a liquid proof manner by said tuck-over ap; and

(c) said pair of slits being spaced apart a distance such that the cut edges formed thereby are held and sealed in a liquid proof manner between their associated fold-under panel and bottom closure panel inner surfaces.

2. The container as defined in claim 1, wherein said tab extends a distance approximately two-fifths the overall width of its bottom closure panel.

3. In a container of paperboard or the like having an overall surface of thermoplastic material that becomes activated adhesively when subjected to heat, said container comprising the combination of a tubular body having a side seam fiap, a top closure on said body, first and second pairs of opposed bottom closure panels connected to said body, said second pair of bottom closure panels being triangular in shape and infolded between said body and said first pair of bottom` closure panels, two pairs of triangular fold-back panels each pair of which is connected to a respective one of said triangular bottom panels and to respective ones of said first pair of opposed bottom closure panels, said fold-back panels being folded against the inside surface of said rst pair of opposed bottom closure panels and with adjacent edges of each pair of fold-back panels abutting each other, a tuck-in flap integral with one of said first pair of bottom closure panels and inserted between the other bottom closure panel of said first pair and the fold-back panels thereagainst, a tuckover flap integral with and extending over the other one of said first pair of bottom closure panels, said tuck-over flap extending over and beyond said tuck-in flap, the improvement therein comprising:

(a) said tuck-in fiap having a pair of spaced parallel slits extending normal to the free edge thereof so as 5 6 to dene a fold-under tab in the middle of said tuck- References Cited in ap, (b) wherein when said fold-under tab is folded against UNITED STATES PATENTS the outer surface of its associated bottom closure 2,186,777 1/ 1940 Best 229-39 panel the free edges of said tab are sealed in a liquid 5 3,120,33 3 2 /1964 Seiple 229 37 proof manner by said tuck-over ap; and (c) said pair of slits being spaced apart a distance FOREIGN PATENTS such that the cut edges formed thereby are held and sealed in a liquid proof manner between their asso- 9201999 3/1963 Great Brltam ciated fold-under panel and bottom closure panel 10 inner surfag, DAVID M. BOCKENEK, Przmary Exammer. 

